I've recently changed from oil to gas ch. I am left with two large metal oil storage tanks with oil sludge in the bottom. How do I get rid of them? I assume I can't take an angle grinder to them without blowing myself up. Is there anything I can do myself or will I need a waste company to do it (for large fee)? Any ideas of the type of company (or any companies you know that do it - my nearest town is Nuneaton, near Coventry/Leicester) or about how much to pay? Many thanks for any help anyone can give.